1. Field of the Invention
The present invention relates to a master input device for remotely operating a slave manipulator and a master-slave manipulator comprising the master input device.
2. Description of the Related Art
Robotic surgical treatment has recently been investigated to implement labor-saving medical facilities. In the field of surgery, various proposals are made for manipulator systems in which a manipulator with a multidegree-of freedom (or multi-joint) arm is used for the treatment of a patient. In one such known manipulator system (master-slave manipulator), the manipulator (slave manipulator) configured to directly contacts the patient's body cavity can be remotely operated by a master input device that is located at a distance from the slave manipulator. Normally, in the master-slave manipulator, the position/orientation of an operating unit of the master input device is input as a command value to a controller. In the controller, an inverse kinematics computation for the distal end portion of the slave manipulator is performed based on the command value of the position/orientation of the operating unit. Thereupon, drive amounts of joints of the slave manipulator are calculated, and the joints are drivingly controlled based on the calculated drive amounts. For this control, it is necessary to detect the position/orientation of the operating unit of the master input device. Conventionally, the position/orientation of the master operation input device is detected by means of a sensor attached to the operating unit of the input device.
If the sensor used to detect the position/orientation of the operating unit is of only a single system, the detection cannot be achieved in case of failure of the sensor. A method of duplexing sensors (e.g., Jpn. Pat. Appln. KOKAI Publication No. 6-168530) is a known way to avoid this. If the technique of this patent document is applied to the master input device, the position/orientation of the operating unit of the input device can be detected by means of a sensor of an alternative system in case of failure of a sensor of one system.